Muslims defeating the two superpowers of that time (combined) - the Byzantines and Sassanids; in my opinion is much more humiliating (for Byzantines and Sassanids).
Despite the Byzantines and Sassanids being significantly superior to the Muslims in terms of experience, organisation, discipline, economic, logistic, numerical strength, technology, size, and ect... Muslim armies managed to defeat them despite being outnumbered by massive numbers in almost every battle. Overall kill ratio was around 1:10/1:15 - these series of victories in such a manner have never been rivaled.